1. Field of the Invention
The present invention relates to a drive mechanism for a magnetic recording head for a camera which uses a silver salt film bearing a magnetic recording medium.
2. Related Background Art
A system comprising a film having a magnetic track provided thereon in addition to an optical image recording area and a camera for using it has been recently proposed. It is intended to read film information (such as a film sensitivity and a photographed frame count) which has been prerecorded on a magnetic track into a control circuit of a camera and write photographing information (such as a diaphragm value and a shutter speed) onto the magnetic track.
In this system, a magnetic head arranged on the camera is pressed to the magnetic track of the film, but since a load to feed the film is high if the film is fed while the magnetic head is pressed to the film, it has been proposed to retract the magnetic head from the film surface when it does not record the information.
In order to prevent positional offset of the magnetic head relative to the width of the magnetic track, it has also been proposed to provide a reference member which is substantially integral with the magnetic head and apply a biasing force to continuously abut the reference member against a film edge so that the magnetic head follows even if the film shifts widthwise, to prevent the offset from the magnetic track.
However, in this mechanism, if the film is retracted from the pressed position to the film when the film is to be fed, the position of the magnetic head may be shifted due to the widthwise shift of the film under feeding. Since the reference member is biased to abut against the film edge, the reference member interferes with the film surface when the magnetic head is to be moved into the pressed position after the magnetic head has been retracted so that the reference member has been away from the film edge. Thus, the movement of the magnetic head is impeded.
In order to prevent this problem, it may be possible to make the reference member sufficiently long to assure that it does not leave the film edge even when the magnetic head is in the retracted position, but this is not preferable because the biasing force which is continuously applied to the film edge from the reference member acts as a load in feeding the film.